The presently disclosed embodiment relates to an electromagnetic vibrating diaphragm pump for suctioning and discharging fluid such as air by vibrating an oscillator having a magnet by means of AC drive of an electromagnet so as to vibrate the diaphragms fixed to the both ends of the oscillator. More particularly, it relates to an electromagnetic vibrating diaphragm pump capable of efficiently vibrating the diaphragms and preventing the performance degradation of the pump, even in case the pressure in a compression chamber of a pump casing adjacent to the diaphragm is high, including the case where the gas to be suctioned is pressurized with flammable gas, for example.
As a schematic view of a diaphragm pump having diaphragms on its both sides, for example, is shown in FIG. 5, the electromagnetic vibrating diaphragm pump is provided with diaphragms 120 made of rubber, etc. fixed on the both ends of an oscillator 110 having two magnets 111a, 111b made of permanent magnets, etc. fixed to a supporting member 112 and with two electromagnets 130a, 130b provided in a manner to face the magnets 111a, 111b. Moreover, a frame 140 is provided in such a manner that the outer peripheries of the diaphragms are fixed to the frame 140 so as to cover the electromagnet 130a, 130b part, and the outer sides of the diaphragms 120 are covered by pump casings 150 each comprising a compression chamber 151, a suction chamber 152 and an exhaust chamber 153. A suction valve 152a is provided between the compression chamber 151 and the suction chamber 152 so that air is injected into from the suction chamber 152 when the pressure in the compression chamber 151 decreases, and an exhaust valve 153a is provided between the compression chamber 151 and the exhaust chamber 153 so that the exhaust valve 153a opens to discharge air to the exhaust chamber 153 when the pressure in the compression chamber 151 increases (see patent document 1, for example).
In the electromagnetic vibrating diaphragm pump with this structure, assuming two magnets 111a, 111b are provided on the oscillator 110 with the polarity shown in the drawing, the oscillator 110 moves to the left due to the attraction and repulsion of north pole and south pole of the magnets 111a, 111b, when current flows into exciting coils 132 so as to generate south pole on the central part of an E-shaped iron core 131 of the electromagnet 130a located on the upper side of the drawing and north pole on both sides of the E-shaped iron core. Moreover, when the phase of an AC source is reversed so that the direction of the current is turned in an opposite manner, the south pole and north pole of the electromagnets 130a, 130b shown in the drawing are reversed so that the oscillator moves to the right this time. As a result, the oscillator 110 oscillates in accordance with the phase change in the AC source. In this regard, the electromagnet 130b located on the lower side of the drawing functions in the manner same as the upper electromagnet, and reversing the direction of the current, such as by reversing the direction of winding the exciting coil and by changing the phase of the AC source to be applied in a manner to differ from that on the upper electromagnet 130a by 180 degrees, changes the polarity of the central part of the E-shaped iron core 131 as shown in FIG. 5.
With a focus on a pump casing 150 on the right side of the drawing, for example, when the oscillator 110 moves to the left in the drawing in accordance with this oscillation of the oscillator 110, the diaphragm 120 is also pulled to the left, and the volume of the compression chamber 151 increases so as to open the suction valve 152a to allow gas to flow from the suction chamber 152 into the compression chamber 151. Subsequently, when the oscillator 110 moves to the right, the diaphragm 120 is also pulled to the right, and the volume of the compression chamber 151 decreases so as to close the suction valve 152a and open the exhaust valve 153a, forcing the gas in the compression chamber 151 out into the exhaust chamber 153. By repeating this action, pumping action is performed so as to allow gas and the like of a predetermined amount to be discharged.
Additional background information may be found in Japanese publication JP 2008-150959 A.